It sounds like someone threw an ice ball in the past and the school just banned all snowballs.

The College Fix reports:

Public university forbids students from throwing snowballs

Delaware State University forbids its students from throwing snowballs, a policy that a school official says is due in part to the potential “harm” that snowball fights pose to those on campus.

The rule, outlined in the school’s Division of Student Affairs Student Judicial Handbook, lists “the throwing of snowballs on University grounds” under the “personal violations” category, alongside violations such as “being in the bath/shower areas of the opposite sex” and “making threats of violence or intimidation.”

“This was made a rule due to the students throwing snowballs in the residential halls and there being the potential to harm others with hard, iced-over snow,” Lawan D. Lanier-Smith, assistant director of judicial affairs, told The College Fix via email.

Delaware State University’s public relations department did not respond to requests for comment from The Fix regarding the snowball policy.

Students who violate rules in the Student Code of Conduct at the University of Delaware, will be subject to disciplinary action. Under the Student Judicial System, the types of sanctions that can be imposed on students include, but are not limited to, warnings, official reprimands, community service, fines, and disciplinary probation.

Along with banning snowballs, Delaware State University also forbids the “use [and] possession of water guns, super soakers, etc. on University premises or during University activities.”